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Full text of "irisGraphics :: IRIS 3024 Color Ink Jet Printer Setting Color Values"

IRIS GRAPHICS 3024 COLOR INK JET PRINTER 

SETTING COLOR VALUES 

By using crystal-stimulated glass capillary nozzles, one million 
droplets of Ink per second per color are generated on the IRIS 3000 series 
printer. Zero, one, two, three, or up to 31 of these droplets may be 
printed at any particular pixel location on the paper. Patented electronics 
control the charging/uncharging of the appropriate number of droplets. 
Uncharged droplets form a single dot of Ink on the receiving media; charged 
droplets are deflected with high voltage Into the waste system. See Figure 
1, "IRIS Series 3000 Ink Jet Printer, Stimulated Nozzle." 

Two techniques are available to the on-line system user on the IRIS 
3000 series printer for controlling color. Both techniques specify the 
precise number of droplets of each color to be printed at every pixel 
location. The first technique (available on all systems) defines contrast 
and density for each of the four colors; a lookup table 1s constructed from 
the parameters. The second technique allows a host system to directly load 
the system 1 s color lookup tables, overriding the Internal canputed tables. 

Both techniques depend on 8 bit Input color data and the current pixel 
location In a 4 by 4 matrix. The system tracks the current pixel's row and 
column location within this 4 by 4 matrix* and with that information, can 
define droplet patterns over the entire to 255 input data range. 











12- 


■bit 














8 


bits 


(inp 


ut data) 


address 


Color 


val 


ue 


















> 


Lookup 




-> 


5 


bits 


(number of 


2 


bits 


(row 


location) 






Table 








ink 


droplets, 


2 


bits 

„1 


(col 


umn locati 


on) 















to 31) 



With tMr ■»#i'b<&" at the start of ..* print* the system will compute and 
unload the color lookup table* The number. of droplets to to® printed at a 
■particular . plwl ideation "4»P*fl<* ' on th$ follow! rig equation* 

table value * Cden$1ty/10Q*) ',,*.81 ; * Cdat*L.value/256) ** contrast, 

where table value = r number Of drop! els to print* 

density ranges frioM to %0S> In 1% increments* 
dat^val ue ranged frcitf 0'" ttf 255'/' ■ ' *' v r ;;: *' v; - 
contrast ranges from 1,0 to 2#5> in 0*1 increments* 

This &qmtiph-yW4& a whole number and' a: f rscti OftV -The sy stem < calculates 

the fraction" at~"rt/£6 % that 1 %$ t&e number of ltftfcr remaining, ' : -.' r. ;<<■•'•;■,, ' 




en 



-2- 

If the value of the remainder (number of sixteenths) 1s greater than or 
equal to the matrix value at the row and column location* the whole number 
plus one 1s loaded Into the table. If the value of the remainder 1s less 
than the matrix value at the row and column location, the whole number 1s 
loaded. The 4 by 4 matrix scheme 1s modeled on an ordered dither technique 
(utilized 1n binary printing technologies): 



16 


8 


14 


6 


4 


12 


2 


10 


13 


5 


IS 


7 


1 


9 


3 


11 



Appendix 1 illustrates several examples. 

When printing each pixel, a table address 1s constructed of the 
Incoming data values and the row and column location to be printed, and the 
table value 1s used to control the number of Ink droplets printed. 



MsthQd 2 



This technique, available on on-Hne systems only, allows the user to 
override the Internally generated tables discussed above and to be 1n full 
control of the printer 1 s color lookup table. In particular, 1f the graph 
below Illustrates a desired map of input data values (0 to 255) to output 
number of droplets (0 to 31), then a color lookup table can be built to 
accomodate this mapping. 




Aroblefc 



Figure 2* 



2j^ 



-3- 



For purposes of constructing the color lookup table, the 4 by 4 matrix 
1s represented in the following sequence: 



raster I 
line I 
direction I 

I 4 8 12 

1 5 9 13 

2 . 6 10 14 

3 7 11 15 

The color lookup table Itself may be viewed as 16 bytes "wide" and 2S6 bytes 
"long.* The 256 bytes represent incoming data values (0 to 255). There 1s 
a color look-up table for each of the four colors* cyan, magenta, yellow and 
black. Each table 1s 4096 bytes 1n size (16 * 256). 

Matrix Location 
1 2 3 4 ... 14 15 

Input 

Data 1 

Value 2 



§ of droplets to print 

254 
255 

The 16 bytes wide represent the 16 locations 1n the 4 by 4 matrix shown 
above. The table values themselves represent the number of droplets to be 
printed for a particular input value, row and column location. 

Refer to the separate document. "IRIS Interface Specification" for the 
details of downloading color tables from host systems. 



Motes 

The actual maximum number of droplets available per pixel location is 
dependent on drum speed and resolution, according to the following equation; 

maximum number 1,000,000* droplets/second 

droplets/pixel drum speed Cinches/second) * resolution (pixels/ Inch) 

The system will not' check for consistency among variables. If the color 
lookup table requests more droplets than are possible, the system will print 
the maximum physically available, 

sja «created - 10/15/87» 



-4- 
Appendix 1 

Sample Calculations — Method 1 
Using Density and Contrast Yalues to Calculate Color Lookup Table Values 

Drum speed » ISO inches/second (for maximum available number of 

Resolution - 240 pixels/ Inch droplets » 27.8) 

Cyan density = 40% 
Magenta density » 80S 
Yellow density - 5055 
Black density - 40S 

Contrast* all colors * 1.5 

table value ■ (density/100.) * 31 * (dataL.value/256) ** contrast, 



Input Yalue 


Number of Droplets 










Cyan 


Mag? 


mta. 


Yellow 


' Black 


255 


12 5/16 


24 10/16 


15 6/16 


12 5/16 


Row/ Column 












1*1 


12 


24 




15 


12 


1,2 


12 


25 




15 


12 


2*3 


13 


25 




16 


13 


3,2 


13 


25 




16 


13 


4,4 


12 


24 




15 


12 


Input Yalue 


Number of Droplets 






• 




Cyan 


Magenta 


Yellow 


Black 


150 


5 8/16 


11 


1/16 


6 15/16 


5 8/16 


Rowf Column 












1,1 


5 


11 




6 


5 


1,2 


6 


11 




7 


6 


2,3 


6 


11 




7 


6 


3,2 


6 


11 




7 


6 


4,4 


5 


11 




7 


5 



Representative cyan color lookup table values: 

Matrix Location 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 IS (table value) 




1/16 

2 2/16 

5 8/16 

254 12 12 12 13 12 12 12 12 12 13 12 13 12 12 12 12 12 3/16 

255 12 13 12 13 12 12 13 12 12 13 12 13 12 12 12 12 12 5/16 



Input 





















































Data 


1 


















































Value 


. 












• 
























10 











1 








































80 


2 


2 


2 


3 


2 


2 


2 


2 


2 


3 


2 


2 


2 


2 


2 


2 




150 


5 


6 


5 


6 


6 


5 


6 


5 


5 


6 


5 


6 


5 


6 


5 


6